SBI3CMeet the Protists

Hello!I am a protist.We’re tiny, numerous, ancient, and weird.

Kingdom Protista● Proto means First● First eukaryotes on

Earth● 2.1 Billion Years old!● Protist fossils are

called stromatolites.

Hard to classify...● All unicellular● May be colonial –

many single cells living together

● Some are plant-like, others are animal-like.

Protozoa● Animal-Like● Heterotrophs: they

must eat to live● Can move

AmoebaA. Food VacuoleB. Contractile Vacuole can expel

excess waterC. Cell MembraneD. Pseudopodia help it moveE. NucleusF. Pseudopod (singular)G. Cytoplasm

ParameciumA. Cilia for movement, trapping foodB. Contractile Vacuole C. Gullet - like a mouth and throatD. Food VacuoleE. Cell membraneF. CytostomeG. MicronucleusH. Macronucleus

MovementSeveral ways to move:● Cytoplasmic streaming: by making your cytoplasm flow,

you can stretch toward something. Amoebae do this.● Use a propeller, called a flagellum. Euglena use flagella.● Use oars, called cilia. Each cilium constantly goes back &

forth. Paramecia use these.

Algae● Most unicellular● Some large colonial – forms,

like seaweed● Plant-like - have chloroplasts,

carry out photosynthesis● Autotrophs - self feeding.

Chlamydomonas1. Flagella for movement2. Contractile Vacuoles3. Cell wall4. Eyespot is light-sensitive5. Pyrenoid collects CO26. Chloroplast is large, cup-shaped7. *Nucleus

Euglena1. Microtubules of protein2. Contractile vacuole3. Eyespot directs it toward light4. Flagella - movement, trap food5. Cytostome, like a mouth6. Photoreceptor senses light7. Basal body8. Chloroplast9. Pellicle, a type of cell wall

10. Nucleus 11. Nucleolus

Reproduction● Method 1: Copy your nucleus & split in two. This is Binary

Fission.

● Method 2: Copy your nucleus a lot, and split into many cells. This is Multiple Fission.

Reproduction● Method 3: Join a partner & swap some DNA, then go your

separate ways. This is Conjugation.

● Method 4: Make gamete-like cells and fuse them. This is a form of Sexual Reproduction.

Exchange micronuclei

Cells separate

New macronucleus

forms (mitosis)

Old macronucleus

dissolves

Colonial protists● Colonies: many living together● Allows for division of labour and

specialized functions● Safer reproduction, better chance of

survival● Example: Volvox

Ecological Role● Photosynthesis releases O2● Food source for many aquatic &

marine animals● Decomposers, Detritivores ● A few are even symbionts, living

inside other organisms